.banner {
    margin: 0 auto;
    width: 1100px;
    height: 480px;
    position: relative;
    overflow: hidden;
    }
    .banner > ul {
    width: 500%;
    height: 100%;
    display: flex;
    position: absolute;
    left: 0;
    top: 0;
    }
    .banner > ul > li {
        flex:1;
        height: 100%;
        display: flex;
        justify-content: center;
    }
    .banner ol {
        width: 200px;
        height: 30px;
        background-color: rgb(0, 0, 0, .5);
        border-radius: 15px;
        position: absolute;
        bottom: 30px;
        left: 50%;
        transform: translateX(-50%);
        display: flex;
        justify-content: space-evenly;
        align-items: center;
    }
    .banner > ol > li {
        width: 20px;
        height: 20px;
        background-color: #fff;
        border-radius: 50%;
        cursor: pointer;
    }
    .banner > ol > li.active {
        background-color: red;
    }

    .banner:hover > div {
        display: flex;
    }

    .banner > div {
        width: 30px;
        height: 40px;
        background-color: rgb(0, 0, 0, .3);
        position: absolute;
        top: 50%;
        transform: translateY(-50%);
        display: none;
        justify-content: center;
        align-items: center;
        color: #fff;
        cursor: pointer;
        transition: all .3s linear;
    }

    .banner > div:hover {
        background-color: rgb(0, 0, 0, .5);
    }

    .banner > div.left {
        left: 0;
        border-radius: 0 20px 20px 0;
    }

    .banner > div.right {
        right: 0;
        border-radius: 20px 0 0 20px;
    }
